JP2015024440A - Laser welding device for repair - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser welding device for repairs in which a crack can be eliminated easily and certainly without generating burn-through even if a welding posture is downward.SOLUTION: A laser welding device for repairs comprises a laser oscillator 2, a laser head 4 which condenses laser light L from the laser oscillator 2 to irradiate a place to be repaired, a drive part 6 of the laser head 4, a control part 7 and a database 8 which includes a shape index. In the database 8, stored as data are a welding speed, a laser output, a spot diameter and influence of shield gas as a welding implementation condition corresponding to a repairing condition in a case of being determined as good on the basis of a shape index. Upon repairing a crack Wa of a steel material W, a repairing condition being inputted, a welding speed, a laser output and a spot diameter as the optimum welding implementation condition corresponding to a repairing condition from welding implementation conditions stored in the database 8 are selected with consideration of influence of the shield gas, and are outputted to the control part 7.

Description

  The present invention relates to a repair laser welding apparatus suitable for repairing a crack generated in a structural member of an existing structure such as a bridge or a building.

  Conventionally, when a crack has occurred in a steel material (structural member) of an existing structure such as a bridge or a building due to aged deterioration or metal fatigue, for example, a welding repair device using a laser beam has been adopted. By irradiating the generated welding repair location with laser light, the weld repair location is melted to eliminate the crack (see Patent Document 1).

Japanese Patent Laid-Open No. 03-169494

  In repairing a crack generated in the above-described structural member, first, it is required not to leave a crack. Therefore, when cracks are eliminated by the above-mentioned welding repair device, welding is performed with a large amount of heat input to the weld repair location, but welding in a so-called downward posture is performed by irradiating laser light downward. Then, if there is too much heat input to the welding repair location, it will melt off.

  In other words, in the welding repair device using the conventional laser beam described above, in the case of welding in a downward posture, there is a problem that it is not easy to perform the welding without leaving a crack and causing no burnout, Solving this problem has been a conventional problem.

  The present invention has been made to solve the above-described conventional problems, and even if the welding posture is downward, it is possible to easily and reliably eliminate cracks without causing melting. An object of the present invention is to provide a laser welding apparatus for repair.

  The invention according to claim 1 of the present invention made to achieve the above object is a repair laser welding apparatus for melting and erasing a crack generated in a structural member of an existing structure by welding. An oscillator, a laser head for condensing the laser beam supplied from the laser oscillator and irradiating the repaired part where the crack is generated, a drive unit for moving the laser head along the repaired part, and a welding speed , A control unit for controlling the laser output and the spot diameter, and a database having a shape index represented by dividing the penetration depth in a preferable cross-sectional shape after welding construction by the thickness of the structural member, Welding postures such as a downward posture and a lateral posture, which are repair conditions when determined to be good based on the shape index, the thickness of the structural member, and the structural portion The material and the effects of welding speed, laser output, spot diameter and shielding gas as welding conditions corresponding to the repair conditions are accumulated as data, and the database is used to repair cracks occurring in the structural member. By inputting the repair conditions, the welding speed, laser output and spot diameter as the optimum welding conditions corresponding to the input repair conditions are selected from the welding conditions stored in the database. It is characterized in that the structure is selected in consideration of the influence of gas and output to the control unit, and the repair laser welding apparatus having this structure is used as a means for solving the above-described problems.

Here, the shape index H _WL / t expressed by dividing the penetration depth H _WL in the preferred cross-sectional shape after welding construction by the thickness t of the structural member is most preferably 1.0, but FIG. In order to avoid a lack of penetration that causes cracks to remain as shown in (a), it is desirable to set the shape index H _WL / t to 1.0 or more, as shown in FIG. In consideration of melting, it is desirable that the shape index H _WL / t is about 1.1.

  Further, in the repair laser welding apparatus according to claim 2 of the present invention, the database has Q as the amount of heat input to the repair site, A as the laser spot area, φ as the spot diameter, and t as the thickness of the structural member. In this case, a regression equation Q / A = f (φ / t) for estimating the welding speed, laser output, and spot diameter as appropriate welding conditions is adopted. At this time, the spot diameter φ is desirably set larger than the width of the crack.

  Furthermore, depending on the welding conditions, the energy absorbed at the repair location (energy required for breaking the specimen in the Charpy impact test) may be reduced, that is, the toughness of the repair location may be reduced and the required value may not be satisfied. is there.

  Therefore, based on the relationship that the absorbed energy increases when the amount of heat input to the repair location decreases, the welding conditions are determined so that the cooling rate of the repair location is appropriate. Specifically, it is desirable to determine a welding speed, a laser output, and a spot diameter in order to give a heat input restriction to a repair location. In the repair laser welding apparatus according to claim 3 of the present invention, the database includes the database In repairing cracks occurring in structural members, the repairing conditions such as the welding posture, the thickness of the structural member, and the material of the structural member, as well as the toughness after construction, are input and stored in the database. Among the welding conditions, the welding speed, laser output, and spot are set as the optimum welding conditions that correspond to the improvement in toughness after the input repair conditions. The diameter is selected after taking into account the effects of the shielding gas and cooling conditions (natural cooling (cooling exposed to the atmosphere) and forced cooling (cooling that applies fluid such as wind and water)). It is configured to output to the serial controller.

  Furthermore, in the repair laser welding apparatus according to claim 4 of the present invention, the database is configured such that the construction result after welding construction is fed back and accumulated as data.

  Furthermore, the repair laser welding apparatus according to claim 5 of the present invention includes a build-up means for overlaying the recessed portion when the repaired portion has a recessed portion due to thinning. As the overlaying means, hot wire welding or arc welding can be employed.

  In the repair laser welding apparatus according to the present invention, it is common to use a YAG laser or a semiconductor laser as a laser oscillator, but the laser oscillator is not limited to these.

  In the repairing laser welding apparatus according to the present invention, when repairing a crack generated in a structural member, the welding position (downward welding posture), the thickness of the structural member, and the material of the structural member are repair conditions for the control unit. Is input, the optimum welding conditions corresponding to the input repair conditions are selected from the welding conditions stored in the database, and the influence of the shielding gas is taken into consideration and output to the control unit.

  In order to satisfy the welding speed, laser output and spot diameter of the optimum welding conditions, the drive unit, laser oscillator, and laser head are controlled by the control unit, respectively. It will be done easily.

  Further, in the repair laser welding apparatus according to claim 2 of the present invention, when the heat input to the repair site is Q, the laser spot area is A, the spot diameter is φ, and the thickness of the structural member is t, the welding work Since the database has a regression equation Q / A = f (φ / t) for estimating (interpolating) welding speed, laser output and spot diameter as conditions, more appropriate welding conditions can be provided. It becomes.

  Specifically, as shown in FIG. 4, the amount of heat input Q (J / mm) to the repair location can be expressed by dividing the laser output P (J / s) by the welding speed V (mm / s). Therefore, if the laser output P and the spot diameter φ are determined based on the regression equation (regression curve) Q / A = f (φ / t) shown in FIG. 3, an appropriate welding speed V is obtained.

  Further, in the repair laser welding apparatus according to claim 3 of the present invention, when repairing a crack generated in the structural member, the welding posture (downward welding posture) which is a repair condition with respect to the control unit, When the toughness after construction is entered in addition to the thickness and material of the structural member, the optimum welding construction conditions corresponding to the toughness improvement after construction of the entered repair conditions are the values of the welding construction conditions stored in the database. It is selected from the inside, and the influence of the shielding gas and the influence of cooling conditions such as natural cooling and forced cooling are taken into account and output to the control unit.

  And, as the optimum welding conditions for improving toughness after construction, the drive unit, laser oscillator, and laser head are controlled so as to satisfy the welding speed, laser output, and spot diameter that can limit heat input to the repaired part. Therefore, the metal structure after construction is improved to a metal structure with good toughness.

  Furthermore, in the repair laser welding apparatus according to claim 4 of the present invention, since the construction results after welding construction are fed back to the database and stored as data, welding conditions with improved accuracy are provided. It will be possible.

As described above, the shape index represented by dividing the penetration depth H _WL in the preferred cross-sectional shape after the welding construction by the thickness t of the structural member is used for the quality determination of the construction after the welding construction. The shape index can be managed based on the shape and width of the weld bead on the back side of the repair location determined from the fatigue strength required for the repair location after welding.

  Here, the adequacy of the above-mentioned welding construction related to toughness improvement after construction is evaluated by measuring the Vickers hardness of the repaired part using the correlation between absorbed energy and hardness. In other words, the construction management can be performed with the hardness as an index.

  Furthermore, in the repair laser welding apparatus according to claim 5 of the present invention, since there is a build-up means for performing build-up, it is possible to cope with crack repair when there is a dent in the repair location. Become.

  According to the laser welding apparatus for repair according to the present invention, even if it is repair welding in a downward posture, a very excellent effect that it is possible to easily and surely erase cracks while avoiding burn-through. Is brought about.

It is a schematic diagram which illustrates schematically the laser welding apparatus for repair which concerns on one Embodiment of this invention. It is a figure (a), (b) explaining the shape index of the database in the laser welding apparatus for repair of FIG. It is a graph explaining the regression formula of the database in the laser welding apparatus for repair of FIG. It is a figure explaining the relationship between the heat gain in the regression formula of FIG. 3, a laser output, and a welding speed. 2 is a graph used to determine optimum welding conditions in the database of the repair laser welding apparatus in FIG. 1. It is a graph used when considering the influence of the material of a structural member, when determining the optimal welding construction condition in the database of the laser welding apparatus for repair in FIG. It is a graph used when considering the influence of the presence or absence of shielding gas when determining the optimal welding construction condition in the database of the laser welding apparatus for repair in FIG. In the database of the laser welding equipment for repair in Fig. 1, the relationship between the absorbed energy and the amount of heat input used to determine the heat input to the repair site as the optimum welding operation condition corresponding to the toughness improvement after welding is shown. It is a graph to show. It is a graph which shows the relationship between the absorbed energy and hardness used for evaluating the validity of the welding construction which concerns on the toughness improvement after welding construction in the database of the laser welding apparatus for repair in FIG. It is a schematic diagram which illustrates schematically the laser welding apparatus for repair which concerns on other embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a repair laser welding apparatus according to an embodiment of the present invention.

  As schematically shown in FIG. 1, this repair laser welding apparatus 1 melts and erases a crack Wa generated in a steel material (structural member) W of an existing structure by welding. And a laser head 4 for condensing the laser beam L supplied from the laser oscillator 2 by the built-in optical system 3 and irradiating the repaired part where the crack Wa is generated, and the laser beam L from the laser oscillator 2 as a laser. An optical fiber 5 that leads to the head 4, a drive unit 6 that moves the laser head 4 along the repaired location and moves it closer to and away from the repaired location, and a control unit 7 that controls the welding speed, laser output, and spot diameter are provided. In this embodiment, the focal point LF of the laser beam L is set to be located outside the steel material W.

Further, the repair laser welding apparatus 1 includes a database 8 having a shape index expressed by dividing the penetration depth H _WL in a preferable cross-sectional shape after welding by the thickness t of the steel material W. As shown in FIG. 2 (b), H _WL / t is preferably set to 1.0 or more, and more desirably, in order to avoid the lack of penetration that causes the remaining cracks shown in FIG. 2 (a). The shape index H _WL / t is set to about 1.1.

The database 8 includes a welding condition, a thickness t of the steel material W, a material quality of the steel material W, and a welding operation corresponding to the repair condition when it is determined as good based on the shape index H _WL / t. The effects of welding speed V, laser output P, spot diameter φ, and shielding gas as conditions are stored as data, and repair conditions are input to this database 8 for repairing a crack Wa occurring in the steel material W. Therefore, the welding speed V, laser output P, and spot diameter φ as the optimum welding conditions corresponding to the repair conditions entered from the welding conditions accumulated in the database 8 are taken into account by the influence of the shielding gas. Is selected and output to the control unit 7.

  In this case, the database 8 indicates that the amount of heat input to the repair site is Q, the laser spot area is A, the spot diameter is φ, and the thickness of the structural member is t. It has a regression equation Q / A = f (φ / t) for estimating the spot diameter. By using this regression equation Q / A = f (φ / t), more appropriate welding conditions are output. Can be done.

  Specifically, as shown in FIG. 4, by dividing the laser output P (J / s) by the welding speed V (mm / s), the amount of heat input Q (J / mm) to the repaired part is expressed. Therefore, an appropriate welding speed V can be obtained by determining the laser output P and the spot diameter φ based on the regression equation (regression curve) Q / A = f (φ / t) shown in FIG. It is like that. It can be seen from the graph of FIG. 3 that this regression equation can be used for both the structural member (SM400) containing a large amount of carbon and the structural member (SM400) containing a small amount of carbon. It can be seen that the above regression equation can be used regardless of the amount of carbon contained in SM400).

  Here, depending on the welding conditions, the energy absorbed at the repair location (energy required for breaking the test piece in the Charpy impact test) decreases, that is, the toughness of the repair location decreases and the required value cannot be met. There is.

  Therefore, as shown in the graph of FIG. 8, the welding conditions are determined so that the cooling rate of the repaired part becomes appropriate based on the relationship that the absorbed energy increases when the heat input Q to the repaired part decreases. ing.

  Specifically, the welding speed V, laser output P, and spot diameter φ are determined in consideration of the effects of shielding gas and cooling conditions such as natural cooling and forced cooling in order to limit the heat input at the repair location. Are output to the control unit 7.

Further, in the repair laser welding apparatus 1, the quality of the construction is judged based on the shape index H _WL / t after the welding construction, and the result is fed back to the database 8 and accumulated as data.

When repairing the crack Wa generated in the steel material W using the repair laser welding apparatus 1 configured in this way, the welding posture (downward welding) which is a repair condition with respect to the control unit 7, When the thickness t and the material of the steel material W (in this case, carbon steel (SM400) and carbon steel (C multi SM400) containing a little more carbon than the carbon steel (SM400)) are input, the graph of FIG. As shown, the optimum welding conditions corresponding to the input repair conditions are selected from the welding conditions accumulated in the database 8 based on the shape index H _{WL /} t (≈1.1), That is, after determining the optimum laser output P and spot diameter φ from the X-axis heat input parameter, an appropriate welding speed V is determined.

  At this time, as shown in the graph of FIG. 6, the database 8 contains a small amount of carbon as the steel material W, for example, carbon steel having a thickness t of 9 mm (C small SM400) and carbon having a thickness t of 12 mm. Steel (C-small SM400) is accumulated as data that the heat input parameter is less inclined at 100 to 150 (J / mm · mm) and the weldability is good. That is, as in the case of different materials such as stainless steel (SUS) and carbon steel (SM400), the difference in the workability due to the difference in the amount of carbon contained in the same carbon steel affects the influence of the material of the steel material W. It is accumulated as data to consider.

  The database 8 also stores data that considers the effect of the presence or absence of shielding gas, which is a repair condition. As shown in the graph of FIG. 7, the amount of carbon contained is medium, for example, the thickness t is In the case of carbon steel of 9 mm (SM400 in C), the influence of the presence or absence of shielding gas is large, and the amount of carbon contained is large, for example, in the case of carbon steel (C multi SM400) having a thickness t of 9 mm Is accumulated as data that the influence of the presence or absence of shielding gas is small.

  Next, by using the regression equation Q / A = f (φ / t) where Q is the amount of heat input to the repair site, A is the laser spot area, φ is the spot diameter, and t is the thickness of the structural member, The welding speed, laser output, and spot diameter as further appropriate welding conditions are estimated (interpolated), and the influence of the shielding gas is taken into consideration and output to the control unit 7.

  In this embodiment, if the post-construction toughness is input to the control unit 7 in addition to the welding posture (downward welding), the thickness t of the steel material W, and the material of the steel material W, the post-construction of the input repair conditions The optimum welding conditions corresponding to the toughness improvement are selected from the welding conditions stored in the database 8, and the effects of shielding gas and cooling conditions such as natural cooling and forced cooling are also taken into account. It is output to the control unit 7.

  In order to satisfy welding speed, laser output, and spot diameter that can limit heat input to the repair location, the drive unit 6, the laser oscillator 2 and the laser head are the optimum welding conditions corresponding to the improvement in toughness after the construction. The optical system 3 of 4 is controlled by the control part 7, and each operates, and welding construction is performed.

After this welding operation, the quality determination of the welding operation based on the shape index H _WL / t is made, and the result is fed back to the database 8 and accumulated as data.

  In addition, as shown in FIG. 9, the validity of the above-mentioned welding construction related to toughness improvement after construction is correlated between absorbed energy and hardness, and the Vickers hardness of the repaired part is measured. It is evaluated by doing. For example, when the Vickers hardness at the repair location is 247 (HV), it can be evaluated that the absorbed energy at the repair location is approximately 27 (J).

  As described above, in the repair laser welding apparatus 1 of this embodiment, when repairing the crack Wa of the steel material W, the control unit 7 has a welding posture (downward welding) as a repair condition, the thickness t of the steel material W, and the steel material. If W is input, the optimum welding condition corresponding to the input repair condition is selected from the welding conditions stored in the database 8, and the control unit 7 also takes into account the influence of the shielding gas. The drive unit 6, the laser oscillator 2, and the laser head 4 are each operated in response to a command from the control unit 7 so as to satisfy the welding speed V, the laser output P, and the spot diameter φ of the optimum welding conditions. Therefore, it is possible to easily perform welding repair without remaining cracks and burnout.

  In the repair laser welding apparatus 1 of this embodiment, the regression equation Q / A = f (φ / t) for estimating (interpolating) the welding speed V, the laser output P, and the spot diameter φ as welding conditions is a database. Since 8 has, much more appropriate welding conditions will be provided.

  Further, in the repair laser welding apparatus 1 of this embodiment, if the welding posture (downward welding), the thickness t of the steel material W, and the material of the steel material W are input to the control unit 7, the toughness after construction is input. The optimum welding conditions corresponding to the toughness improvement after construction of the entered repair conditions are selected from the welding conditions stored in the database, and the effects of shielding gas, natural cooling, forced cooling, etc. The effect of the cooling condition is also taken into account and output to the control unit 7.

  And, as the optimum welding construction conditions corresponding to the improvement of toughness after construction, the drive unit 6, laser oscillator 2 and laser so as to satisfy the welding speed, laser output and spot diameter that can limit the heat input to the repaired part Since the optical system 3 of the head 4 is controlled by the control unit 7 and operates, the metal structure after construction is improved to a metal structure having good toughness.

  Furthermore, in the repair laser welding apparatus 1 of this embodiment, since the Vickers hardness of the repaired part is measured, the validity of the welding construction related to the toughness improvement after construction can be evaluated. It will be possible to perform construction management with the index as a measure.

  Furthermore, in the repair laser welding apparatus 1 of this embodiment, since the construction results after welding construction are fed back to the database 8 and stored as data, as repair welding construction for cracks Wa is repeated, High-precision welding conditions will be provided.

  FIG. 10 shows a repair laser welding apparatus according to another embodiment of the present invention.

  As schematically shown in FIG. 10, this repair laser welding apparatus 1 has hot wire welding as a build-up means for overlaying the recess Wb when there is a recess Wb due to thinning at the repair location. The mechanism 10 is provided, and the other configuration is the same as the repair laser welding apparatus 1 according to the previous embodiment.

  The hot wire welding mechanism 10 includes a wire supply drum 11, a wire holder 12, and a wire welding power source 13. The wire supply drum 11 continuously supplies the welding wire FW to the wire holder 12. The wire welding power source 13 builds up the dent Wb by energizing and melting the welding wire FW.

  In the laser welding apparatus 1 for repair, when the surface of the repair site is rusted, for example, the crack repair of the dent Wb formed in order to remove the rust, or the surface of the repair site is reduced by corrosion. It will be possible to cope with crack repair in a situation where the recess Wb is formed.

  In the above-described embodiment, the case where the repair laser welding apparatus 1 is used for welding in the downward posture is shown. However, the welding posture is not limited to the downward posture. Naturally, it can be used for posture welding.

  The configuration of the repair laser welding apparatus according to the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention.

DESCRIPTION OF SYMBOLS 1 Laser welding apparatus for repair 2 Laser oscillator 4 Laser head 6 Drive part 7 Control part 8 Database 10 Hot wire welding mechanism (building-up means)
L Laser light W Steel (Structural member)
Wa Crack Wb Depression

Claims (5)

A laser welding apparatus for repair that melts and erases a crack generated in a structural member of an existing structure by welding,
A laser oscillator;
A laser head for condensing the laser beam supplied from the laser oscillator and irradiating the repaired part where the crack is generated;
A drive unit for moving the laser head along the repair location;
A control unit for controlling the welding speed, laser output and spot diameter;
A database having a shape index represented by dividing the penetration depth in a preferable cross-sectional shape after welding construction by the thickness of the structural member,
In the database, as a welding condition corresponding to this repair condition, the attitude of welding, the thickness of the structural member and the material of the structural member, which are repair conditions when determined to be good based on the shape index The effects of welding speed, laser output, spot diameter and shielding gas are accumulated as data,
In the database, the repair condition is input when repairing a crack generated in the structural member, so that the optimum condition corresponding to the input repair condition is selected from the welding conditions stored in the database. A repair laser welding apparatus, wherein welding speed, laser output, and spot diameter as welding conditions are selected in consideration of the influence of the shielding gas and output to the control unit.   The database has the welding speed, laser output, and spot diameter as appropriate welding conditions, where Q is the amount of heat input to the repair location, A is the laser spot area, φ is the spot diameter, and t is the thickness of the structural member. The laser welding apparatus for repair according to claim 1, which has a regression equation Q / A = f (φ / t) for estimating   In the database, when repairing a crack generated in the structural member, the post-construction toughness is inputted in addition to the welding posture, the thickness of the structural member, and the material of the structural member, which are the repair conditions. In order to limit the heat input to the repaired part as the optimum welding construction condition corresponding to the toughness improvement after construction of the inputted repairing condition from among the welding construction conditions accumulated in the database, the welding speed 2. The laser welding apparatus for repair according to claim 1, wherein the laser output and the spot diameter are selected and output to the control unit in consideration of the influence of the shielding gas and the cooling condition.   The repair laser welding apparatus according to any one of claims 1 to 3, wherein a construction result after welding construction is fed back and accumulated as data in the database.   The repair laser welding apparatus according to any one of claims 1 to 4, further comprising a build-up means for performing build-up on the recessed portion when the repaired portion has a recessed portion due to thinning.

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